Rock crushing is commonplace in industry. For example, in the mineral processing industry, ore samples are routinely crushed to liberation sizes in order to separate the valuable minerals from the waste rock. High pressure grinding rolls, termed HPGR, are commonly used for this purpose. It is often advantageous to know the specific energy required to crush a particular type of rock, as this can be of assistance in sizing electrical services and in equipment selection in plant design. Existing methods for calculating crushing energy generally require about 250 kilograms of rock sample and base the energy analysis on electrical energy consumed during a crushing operation. The large sample masses required renders these methods inconvenient.